How Eccentric Screw
Pumps Work...

Eccentric screw are a type of progressive cavity pump that consist of only one moving part - a driven metal (inelastic) rotor, rotating within an elastomer lined (elastic) stator. As the rotor turns, chambers are formed between the rotor and stator. These chambers progress axially from the suction to discharge end, moving the fluid.
 
By increasing the pitch of the rotor and stator, additional chambers or stages are formed. The design allows pumping in both directions, a high suction lift and cautious pumping. Due to the numerous combinations of material for rotor and stator and the cautious pumping with extremely low shear forces.